Download Unit 1 - Climate and Change

Unit 1 - Climate and Change
2.1 How and why has climate changed in the past?
a Climate has changed in the past through natural causes, on timescales ranging from
hundreds to millions of years.
Examine past climate change on different timescales, including the ‘Ice Ages’ in the
Quaternary Period and UK climate since Roman times.
Explore the natural causes of climate change, including asteroid collisions, orbital
changes, volcanic activity and variations in solar output.
b Natural climate change in the past has affected people and the environment.
Examine the impact of a short-term historical event on people and the environment,
e.g. the ‘Little Ice Age’.
Consider the impact of major climatic changes in geological time, e.g. the mass
extinction of megafauna at the end of the Quaternary Period.
Why did the medieval warm period allow The Vikings to go to Greenland?
During the Medieval Warm period temperatures were warmer, this meant crops grew well
and there was increasing wealth and population. It also allowed for easier sea
transportation without dangerous sea ice, which meant that they colonised locations such
as Greenland.
Key Idea: Natural climate change in the past has affected people and the environment.
The Frozen Thames, a painting by Abraham
Hondius from 1677. The Thames froze over
regularly during the period of the Little Ice
Age, but it has not frozen in nearly two
centuries, since before the reign of Queen
Victoria. Warmer winters are one reason. The
building of bridges and embankments - which
caused the river to flow faster - is another.
Question: Describe how climate change in the past, such as the Little Ice Age, affected
people and ecosystems. (4 marks)
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
1
Model Answer: Colder climatic conditions meant low temperatures and frosts killed many crops, or
yields were lower (1), this meant that many people became ill due to lack of food, or starved to
death. (1)
The death of natural vegetation in forests due to the colder temperatures caused a lack of food for
wild animals such as deer (1), which meant these species died and their numbers declined (1). They
were also hunted more by people as there was no other food for people to eat.
The Extinction of Megafuna
During the end of the Pleistocene ice age, many lasrge animals such as the woolly mammoth and
sabre tooth tiger, however as the ice melted 135 species of animal became extinct. Many scientists
believe this was because the animals failed to adapt to the new climatic conditions, many places
were drier, and the changes to the food chains. An alternative view is that at the end of the ice age
many humands migrated North to these new lands and hunted these animals to extinction.
How has The UK’s climate changed?
•
Cooler during the Roman period (100 BC).
•
Warmed up around 400 AD, which peaked between 1100 and 1300 AD in Medieval warm
period.
•
Declined 1400- 1850 (Little Ice Age) 1850- 2000 stable.
•
2000 dramatic increase- modern climate change.
What caused the Climate Change?




Orbital theory – The earth’s orbit has now become an ellipse rather than a circular rotation
around the sun, therefore affecting the amount of sunlight we receive.
Solar Output – Images of the sun show black spots on the surface of the sun which are know
as sunspots. The more sunspots that are presented the more radiation seems to reach the
earth and therefore warms the planet.
Volcanic Activity – Major volcanic eruptions are known to block out sunlight with the huge
ash clouds and reduce the surface temperature of the planet. For example in 1991 Mt
Pinatubo had a major eruption and cooled the planet by 1.2oC.
Asteroid collisions – a large asteroid or meteorite hitting earth would throw up a large cloud
of dust and therefore block out sunlight and cool global temperatures.
Question: Explain natural causes of climate change. (6 marks)
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
2
Model Answer: Orbital changes impact the Earth’s climate because the Earth’s climate varies
between elliptical (egg shaped) to more of a circular route. This means at some times Earth passes
closer to the sun, and therefore received more radiation making temperatures warmer. At other
times earth is further away, receives less radiation, and temperatures are therefore cooler.
2.2 What challenges might our future climate present us with?
a The climate of the UK appears to be changing as a result of global changes caused by
human activity.
Investigate the climate of the UK today, including temperature, rainfall and seasonality, and
consider why they might change in the future, including reference to ocean currents and air
masses.
Examine how human activities produce rising levels of carbon dioxide and methane and how
these contribute to the enhanced greenhouse effect.
b Future climates are uncertain but likely to present major economic and environmental
challenges to the UK and, especially, to people in the developing world.
Consider a range of projections for global temperature change and sea level rise, including
reasons for the uncertainty.
Examine the possible economic and environmental impacts of future climate change for the
UK and in one named developing country, e.g. Bangladesh.
The Enhanced Greenhouse Effect
The greenhouse effect is a natural
process. The gases in the atmosphere
keep the Earth at the correct
temperature. If this didn’t happen life
wouldn’t exist as the Earth’s
temperature would be 33°C (59°F)
lower than at present.
The enhanced greenhouse effect is a
human process. High levels of gases
are in the atmosphere trapping more
heat than we need, warming the Earth.
3
What are the greenhouse gases?
In order, Earth's most abundant greenhouse gases are:
water vapour
carbon dioxide
methane
nitrous oxide
ozone
CFCs
Greenhouse gas
% of
greenhouse
gas
produced
Sources
Warming
power
compared to
carbon dioxide
% increase
since 1850
Carbon dioxide
89%
Burning fossil fuels (coal,
oil, gas), deforestation
which produces carbon
dioxide
1
+ 30%
Methane
7%
Gas pipeline leaks, rice in
paddy fields, cattle
farming.
21 times more
powerful
+ 250%
Nitrous oxide
3%
Jet aircraft engines, cars
and lorries, fertilisers and
sewage farms.
250 times more
powerful
+ 16%
Halocarbons
1%
Used in industry, solvents
and cooling equipment.
3000 times
more powerful
Not natural
4
What will the effect of the enhanced greenhouse be?
Rise sea levels, more severe storms, changes to rainfall patterns and changes to temperature
patterns could affect different parts of the globe in different ways.
Weather in the UK
In the UK our most common weather patterns are shown in the diagram below:
Question: Describe the pattern of rainfall in the UK. Why is there more rainfall in the West of the
British Isles?
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
5
What is relief rainfall?
Many of the mountain ranges in the British Isles occur in the West. The West is therefore more likely
to experience relief rainfall.
Also the most prevailing wind is from the southwest. This wind blows over the Atlantic, bringing
moisture-laden air. The prevailing wind is the most common direction of wind.
6
Key Idea: Future climates are uncertain but likely to present major economic and environmental
challenges to the UK and, especially, to people in the developing world.
Case study: Bangladesh
Environmental Impacts
•
More cyclones due to warmer air and sea temperatures- destroy animal habitats.
•
More water and faster flowing rivers cause flooding and more erosion. People loose land
and this land is silt in the river; this can lead to the death of fish, it increases water
temperatures.
•
Plants and animals are drowned in floods.
•
Slums contaminate rives as sewage in untreated. People have no rubbish disposal and
therefore fly tip.
Social Impacts
•
People lose their incomes (from farming as crops are destroyed) and cannot afford to pay
their rent/ for food/ medical care.
•
People get ill from contaminated water.
•
People die as their food source has been destroyed
Economic Impacts
•
Cities overcrowded and full of slums which expand daily, the government often have to pay
for policing to clear private land that has been settled on.
•
Homes/ businesses/ shops destroyed and land lost, repairs have to be paid for and homes
built.
•
Medical care for people who have been made ill by dirty water is expensive.
•
Search and rescue and shipping emergency supplies are expensive and uses up the few
resources the government have.
7
Case study: UK
What are the potential impacts of climate change for the UK?
Temperatures in the UK have risen by about one degree since the 1970s and, given
the levels of greenhouse gas already in the atmosphere, further warming is inevitable
over the next three decades or so. The government's latest climate change risk
assessment identifies flood risk, and particularly flooding from heavy downpours, as
one of the key climate threats for the UK, alongside stresses on water resources,
threats to biodiversity and natural habitats.
The government estimates that annual damages from flooding alone could increase to
between £2bn and £12bn by the 2080s, an increase of about two to 10 times
compared with current-day estimates. Current government estimates suggest
about 330,000 properties are currently at risk of flooding, and climate change could
increase this to between 630,000 and 1.2m by the 2080s.
The models suggest that the UK could experience warmer, drier summers in the
future. While that may bring some benefits, it could mean increased risk of drought,
and extreme events such as the 2003 heat wave could be the norm by the end of this
century. Heat waves could also heighten pressure on healthcare services, because
older populations are more vulnerable to extreme heat.
There are some benefits to climate change in the UK, which could see new crop
types, or increased yields of crops such as wheat or sugar beet. For some areas of
the UK, climate change could also offer wider opportunities for tourism. And for
wildlife warmer temperatures could increase survival rates for offspring born in winter.
The Guardian, 2013
Read the article above and identify the following impacts:
Environmental Impacts

………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………….
Social Impacts

………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………….
Economic Impacts

…………………………………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………………………………
8